Influence of biochar amendment on removal of heavy metal from soils using phytoremediation by C. roseus and Chrysopogon zizanioides

Abstract

Advances in sustainable toxic heavy metal treatment technologies are crucial to meet our needs for safer land to develop an urban resilient future. The heavy metals bioaccumulate in the food chain due to its persistence in the soil, which poses a serious challenge to its removal and control. Utilisation of hyperaccumulators to reduce the mobility, accumulation, and toxic impact of heavy metals is a promising and ecologically safe technique. Amendments such as biochar, compost and chelates have shown to enhance the phytoremediation efficiency. The potential soil improvement is influenced by the properties of the amendment, plant and metal heterogeneities. In this study, an organic biochar amendment for the 60-day pot experiment using C. roseus, Chrysopogon zizanioides in a heavy metal contaminated soil was applied. The influence of biochar prepared from sugarcane bagasse biochar on phytoremediation of Pb, Zn and Cd from the soil was explored. Biochar amendment rate of 2% had significant effect on the improvement of the morphological characteristics of the plants in comparison to the control. The soil potassium concentrations increased with amendment rates, while the ammonia and phosphorous reduced beyond an optimum biochar content. Heavy metal concentrations in the soil were consistently lower in the amended soil for both plants. The translocation factor (TF) and bioconcentration factor (BCF) exhibited the phytoextraction and phytostabilisation potential of the plants. However, it remains specific to each contaminant, plant and amendment rate. The insights from this study establishes that the synergy between biochar amendment and the selected medicinal plants improved the phytoremediation efficiency.